在网络计划中，工作N最早完成时间为第17天，持续时间为5天。该工_爱下问搜题

搜题请搜索小程序“爱下问搜题”

问题单项选择题

在网络计划中，工作N最早完成时间为第17天，持续时间为5天。该工作有三项紧后工作，它们的最早开始时间分别为第25天、第27天和第30天，则工作N的自由时差为（）天。

A.13

B.8

C.3

D.5

答案

参考答案：B

解析：工作的自由时差是指在不影响紧后工作的最早开始时间的前提下，本工作可以利用的机动时间，因此FFN=min{25，27，30）-17=8。所以B正确。

改错题

短文改错。
     此题要求改正所给短文中的错误。对标有题号的每一行作出判断：
     如有错误（每行只有一个错误），则按下列情况改正：
     此行多一个词：把多余的词用斜线（ \ ）划掉，在该行右边横线上写出该词，并也用斜线划掉。
     此行缺一个词：在缺词处加一个漏字符号（∧），在该行右边横线上写出该加的词。
     此行错一个词：在错的词下划一横线，在该行右边横线上写出改正后的词。
     注意：原行没有错的不要改。

When I was four years old I got ill. I took medicine twice
a day. The medicine had so a bitter taste that I took it mixed in
orange juice. The problem was that I can still taste the medicine.
In a particular afternoon my mother brought the drink in. As
she gave it to me, when the phone rang and she went to answer
it. I looked at the orange drink and decided I couldn't face them,
so I hid the glass behind a pile magazines. Of course, when 61.
my mother was asked," Have you already taken your medicine?"
I said," Yes." I felt very pleased with me. The next day, my
mother found drink when she was doing the housework. She
looked at me serious and said," It's bad to tell lies!"

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单项选择题

下列不是慢性光化性皮炎诊断依据的是（）

A.持久性皮炎或湿疹性皮损

B.可伴有浸润性丘疹或斑块，主要累积于曝光区

C.光激发试验或光斑试验可呈阳性

D.皮肤划痕试验阳性

E.组织病理为慢性湿疹或假性淋巴瘤改变